Abstract

The longitudinal magnetization of a ferromagneticwire which carries an alternating current in the presence of a stationary longitudinal magnetic field varies at twice the frequency of the applied current. This effect discovered by Procopiu has recently been studied by Skórski and Duracz. An analogous effect is observed when the ferromagneticwire is replaced by a wire of a nonideal type II superconductor and the current alternates below the critical value Ic. In the superconducting case, the longitudinal magnetization of the wire may oscillate from strongly paramagnetic to strongly diamagnetic as the conduction current is varied. The frequency of oscillation of the magnetization is twice that of the applied current as in the ferromagnetic case. With the current varying as I=Ic cos ωt the longitudinal magnetization can be described by Mz≈A+B cos (2ωt), where A and B are temperature‐ and field‐dependent parameters. This phenomenon in the superconducting state is shown to arise from helical patterns of induced and conduction current flow in the presence of a longitudinal field.